DNA methyltransferase

By Emily Cartwright, PhD

By Christina Towers, PhD.

Autophagy more than a cytosolic event

Autophagy is a cellular process whereby cytosolic components are broken down and eliminated or recycled. As a homeostatic mechanism, basal autophagic activity eliminates excess or abnormal proteins and organelles1. As an induced process, autophagy may be triggered by various external challenges, such as decreased nutrient and energy resources, and oxidative stress¹.

The polycomb group (PcG) protein, enhancer of zeste homolog 2 (EZH2) is a methyl-transferase that plays a key role in transcriptional gene repression. EZH2 is frequently overexpressed in several malignant tumors, and is often associated with advanced disease stage in many solid tumors.

Enhancer of Zeste homolog 2 (EZH2) is the methyltransferase enzyme responsible for trimethylating lysine 27 on histone H3 to produce H3K27Me3. EZH2 is a polycomb group protein that is an essential epigenetic regulator that is often found deregulated in a wide variety of malignant cancer types.

DNA methyltransferases catalyze the transfer of the methyl group from S-andenosyl methionine (SAM) to DNA. Such methylation has wide ranging function in the cell, including organismal development and cell differentiation. In cancer, abnormal hypermethylation of gene promoter CpG islands can result in transcriptional silencing.